include/apr_hooks.h

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#ifndef APACHE_AP_HOOKS_H
#define APACHE_AP_HOOKS_H

#include "ap_config.h"

/* For apr_array_header_t */
#include "apr_lib.h"

/**
 * @package Apache hooks functions
 */

#define AP_DECLARE_HOOK(ret,name,args) \
typedef ret HOOK_##name args; \
API_EXPORT(void) ap_hook_##name(HOOK_##name *pf,const char * const *aszPre, \
		         const char * const *aszSucc,int nOrder); \
API_EXPORT(ret) ap_run_##name args; \
typedef struct _LINK_##name \
    { \
    HOOK_##name *pFunc; \
    const char *szName; \
    const char * const *aszPredecessors; \
    const char * const *aszSuccessors; \
    int nOrder; \
    } LINK_##name;

#define AP_HOOK_STRUCT(members) \
static struct { members } _hooks;

#define AP_HOOK_LINK(name) \
    apr_array_header_t *link_##name;

#define AP_IMPLEMENT_HOOK_BASE(name) \
API_EXPORT(void) ap_hook_##name(HOOK_##name *pf,const char * const *aszPre, \
		         const char * const *aszSucc,int nOrder) \
    { \
    LINK_##name *pHook; \
    if(!_hooks.link_##name) \
	{ \
	_hooks.link_##name=apr_make_array(ap_global_hook_pool,1,sizeof(LINK_##name)); \
	ap_hook_sort_register(#name,&_hooks.link_##name); \
	} \
    pHook=apr_push_array(_hooks.link_##name); \
    pHook->pFunc=pf; \
    pHook->aszPredecessors=aszPre; \
    pHook->aszSuccessors=aszSucc; \
    pHook->nOrder=nOrder; \
    pHook->szName=ap_debug_module_name; \
    if(ap_debug_module_hooks) \
	ap_show_hook(#name,aszPre,aszSucc); \
    }

/* RUN_ALL runs to the first one to return other than ok or decline
   RUN_FIRST runs to the first one to return other than decline
   VOID runs all
*/

#define AP_IMPLEMENT_HOOK_VOID(name,args_decl,args_use) \
AP_IMPLEMENT_HOOK_BASE(name) \
API_EXPORT(void) ap_run_##name args_decl \
    { \
    LINK_##name *pHook; \
    int n; \
\
    if(!_hooks.link_##name) \
	return; \
\
    pHook=(LINK_##name *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
	pHook[n].pFunc args_use; \
    }

/* FIXME: note that this returns ok when nothing is run. I suspect it should
   really return decline, but that breaks Apache currently - Ben
*/
#define AP_IMPLEMENT_HOOK_RUN_ALL(ret,name,args_decl,args_use,ok,decline) \
AP_IMPLEMENT_HOOK_BASE(name) \
API_EXPORT(ret) ap_run_##name args_decl \
    { \
    LINK_##name *pHook; \
    int n; \
    ret rv; \
\
    if(!_hooks.link_##name) \
	return ok; \
\
    pHook=(LINK_##name *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
	{ \
	rv=pHook[n].pFunc args_use; \
\
	if(rv != ok && rv != decline) \
	    return rv; \
	} \
    return ok; \
    }

#define AP_IMPLEMENT_HOOK_RUN_FIRST(ret,name,args_decl,args_use,decline) \
AP_IMPLEMENT_HOOK_BASE(name) \
API_EXPORT(ret) ap_run_##name args_decl \
    { \
    LINK_##name *pHook; \
    int n; \
    ret rv; \
\
    if(!_hooks.link_##name) \
	return decline; \
\
    pHook=(LINK_##name *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
	{ \
	rv=pHook[n].pFunc args_use; \
\
	if(rv != decline) \
	    return rv; \
	} \
    return decline; \
    }

     /* Hook orderings */
#define AP_HOOK_REALLY_FIRST	(-10)
#define AP_HOOK_FIRST		0
#define AP_HOOK_MIDDLE		10
#define AP_HOOK_LAST		20
#define AP_HOOK_REALLY_LAST	30

/**
 * The global pool used to allocate any memory needed by the hooks.
 * @defvar apr_pool_t *ap_global_hook_pool
 */ 
extern API_VAR_EXPORT apr_pool_t *ap_global_hook_pool;

/**
 * A global variable to determine if debugging information about the
 * hooks functions should be printed
 * @defvar apr_pool_t *ap_debug_module_hooks
 */ 
extern API_VAR_EXPORT int ap_debug_module_hooks;

/**
 * The name of the module that is currently registering a function
 * @defvar apr_pool_t *ap_debug_module_name
 */ 
extern API_VAR_EXPORT const char *ap_debug_module_name;

/**
 * Register a hook function to be sorted
 * @param szHookName The name of the Hook the function is registered for
 * @param aHooks The array which stores all of the functions for this hook
 * @deffunc void ap_hook_sort_register(const char *szHookName, ap_arry_header_t **aHooks)
 */
API_EXPORT(void) ap_hook_sort_register(const char *szHookName, 
                                      apr_array_header_t **aHooks);
/**
 * Sort all of the registerd functions for a given hook
 * @deffunc void ap_sort_hooks(void)
 */
API_EXPORT(void) ap_sort_hooks(void);

/**
 * Print all of the information about the current hook.  This is used for
 * debugging purposes.
 * @param szName The name of the hook
 * @param aszPre All of the functions in the predecessor array
 * @param aszSucc All of the functions in the successor array
 * @deffunc void ap_show_hook(const char *szName, const char *const *aszPre, const char *const *aszSucc)
 */
API_EXPORT(void) ap_show_hook(const char *szName,const char * const *aszPre,
                             const char * const *aszSucc);

/**
 * Remove all currently registered functions.
 * @deffunc void ap_hook_deregister_all(void)
 */
API_EXPORT(void) ap_hook_deregister_all(void);

#endif /* ndef(AP_HOOKS_H) */